A cargo sea faring vessel routinely docks at ports to load cargo and transports it to another port where the cargo can be unloaded. Once the cargo has been unloaded, the vessel is lighter and therefore, in order to compensate for the weight lost, ballast material is filled into specially constructed ballast tanks. This helps the sea faring vessel maintain balance and stability when it travels empty. Seawater is found to be a very convenient ballast material since it is easily available. By installing pumps on the sea faring vessels, seawater could be filled in to the conventional segregated ballast tanks. On reaching the first port, the ballast water was disposed off into the ocean without adequate treatment. This water contained planktons and other marine organisms specific to the port where the ballast material had been loaded. Disposing the ballast water at a different port caused these living organisms to be transferred into another ecological habitat thereby creating several biological hazards and extinction of various living organisms. Thus transfer of ballast water from a port of one country to port of other country poses a big environmental problem and is detrimental to the ecosystem of the place where the new ballast water is disposed off.
The advent of laws governing the disposal of ballast water and the need for adequate treatment of the ballast water has led to extensive research and development worldwide. In 1996, The United States Congress passed the National Invasive Species Act (P. L. 104-332) to stem the spread of non-indigenous organisms by ballast water discharge. The Act reauthorized the Great Lakes ballast management program and expanded applicability to vessels with ballast tanks. The Act requires the Secretary of Transportation to develop national guidelines to prevent the spread of organisms and their introduction into U.S. waters via ballast water of commercial vehicles.
The Act establishes guidelines that require vessels that enter the U.S. waters after operating to undertake ballast exchange in the high seas. In this method, a vessel empties its ballast on the high seas and refills the ballast tanks with the high seawater. However, the emptying of ballast tanks causes an imbalance that makes the exchange of ballast material on the high seas both dangerous and sometimes impossible because of weather conditions.
Therefore, the need for an effective and economical ballast material management apparatus, method or process was felt.
Numerous methods and compositions have been proposed to control and inhibit the growth of various marine plants and animals. In particular, a number of compositions have been proposed to treat water and various surfaces having infestation of zebra mussels and other marine organisms. The various patents cited below represent the prior art for ways to treat the ballast water.
U.S. Pat. No. 6,500,345
This patent discloses an apparatus and method for treating water to be supplied to a ballast tank using a water pathway having a main inlet for connection to a body of navigable open raw water containing sediment and marine organisms, and a main outlet for connection to the vessel's ballast tank. It uses a centrifugal separator to separate sediment and some water from the raw water.
U.S. Pat. No. 6,516,738
This patent discloses the use of ozone through an ozone transport system to treat the ballast material.
U.S. Pat. No. 6,447,720
This patent discloses an ultraviolet disinfection system and method for treating fluids including a configuration and design to function effectively with at least one UV light source or lamp that is not submerged in the fluid.
U.S. Pat. No. 6,053,121
This patent discloses a method and apparatus for exchanging ballast material in a ballast tank of a sea faring vessel as well as a sea faring vessel provided with a system for exchanging ballast material using differences in pressure to drive ballast material in and out of the ballast tanks.
U.S. Pat. No. 5,353,728
An improved tanker ship construction design includes a plurality of liquid cargo tanks distributed in two longitudinal sets along each side of a tanker ship. A plurality of fully protected ballast tanks are distributed longitudinally between the sets of cargo tanks. A passive, gravity-responsive, fluid transfer system provides very rapid fluid communication between selected cargo tanks and adjoining ballast tanks. A gravity responsive fluid transfer system is provided between the respective ballast tanks.
Extensive research and development works is in progress worldwide; the technologies being researched include filtration and physical separation, treatment with chemicals, ultraviolet light, ozone, heat, de-oxygenation, electro-ionization, gas super-saturation and various combinations. These methods are not economical and also pose various other drawbacks. For example, treatment with chemicals such as chlorine introduces harmful chemicals into the water, chemicals used are quite expensive, some methods are not able to handle large amount of water at a high pumping rate. According to the International Maritime Organization (IMO), shipping transfers more than 10 billion tons of ballast material around the globe each year. Thus, using chemicals, ozone, UV rays etc are not economically viable options.
Another common problem faced, which disrupts and damages the marine ecosystem is the spillage of oil caused by oil tankers. In recent times, there have been numerous tanker disasters resulting in major oil spills and there exists need to provide adequate measures to curb and control the spillage. A possible solution could be to provide a shielding that can absorb shocks during collisions that tear apart the oil tanks. The United States made it mandatory that all new tankers operating in U.S. waters to be built with double hull construction and the existing single hull tankers to be modified to suit the required double-hull arrangement or be phased out and scrapped when they reach a predetermined age.
U.S. Pat. No. 6,178,991
This invention comprises of a safety container for storing and transporting environmentally hazardous, in particular explosive substances, such as gasoline, oil, hydrogen, and other fuels, consisting of an extended container closed on all sides, which is provided with filling and emptying devices or openings, and which is integrated into a transport vehicle or associated with such.
The patents listed above identify some measures that have been taken to prevent oil spills. There have been various measures taken to separate the oil spilt from the water as well. This signifies that the damages caused by ballast material being released at various ports and oil spills due to collisions at sea pose a substantial biohazard and there exists a need to rectify the problem as soon as possible.